docs: def addPathway(
              self, pathway_id, pathway_label, pathway_type=None,
              pathway_description=None):
          """
          Adds a pathway as a class.  If no specific type is specified, it will
          default to a subclass of "GO:cellular_process" and "PW:pathway".
          :param pathway_id:
          :param pathway_label:
          :param pathway_type:
          :param pathway_description:
          :return:
          """
  
          if pathway_type is None:
              pathway_type = self.globaltt['cellular_process']
          self.model.addClassToGraph(
              pathway_id, pathway_label, pathway_type, pathway_description)
          self.model.addSubClass(pathway_id, self.globaltt['pathway'])
  
          return